Positioning photonic crystal cavities to single InAs quantum dots

We have investigated the optical properties of planar photonic crystal cavities formed by removing a single hole from a two-dimensional square lattice of air holes etched through a thin GaAs slab. We have demonstrated cavity resonances with quality factors (Q’s) as high as 8500, using an internal light source provided by an ensemble of InAs quantum dots (QDs) grown by molecular beam epitaxy (MBE). The high-Q modes are confined to a very small mode volume, V = 0.7(λ/n)³, making them attractive to study in the context of cavity quantum electrodynamics with single QDs, where a high is needed to observe the strong coupling between an electronic state of the dot and the optical cavity mode. To this end, we have developed an accurate and robust alignment technique that positions a photonic crystal cavity to a single QD with 25 nm resolution. We present the details of this new technology and demonstrate its effectiveness by strategically positioning a number of QDs within photonic crystal cavities at points where the electric field intensity is high.     

Design of electro-optic switching via a photonic crystal cavity coupled to a quantum-dot molecule and waveguides

We demonstrate the possibility to realize an electro-optic switching operation in a weak-excitation limit, where one can control the path of an optical field propagating in a waveguide by suitably varying the applied bias voltage to tune the electron tunnel coupling.     

FDTD simulation of time varying optical vortex phenomena in SOI photonic crystal structures

In this paper we analyze the time varying optical vortex phenomena in the gain photonic crystals built on the silicon-on-insulator (SOI) wafer by using the finite difference time domain (FDTD) method. With launching the optical waves in 1.55 μm wavelength to the SOI rib waveguide, optical vortices are generated and the spinning details are observed at various time steps. The analysis results are helpful to understand the progress of optical vortices which may be utilized for the development of future nonlinear optical switches.     

The beam splitting in the photonic crystal at a degenerate state

In this paper, using the plane-wave expansion and finite difference time-domain methods, the photons behavior in the photonic crystal is investigated. Theoretically, when a polarized wave is incident from the background medium to the photonic crystal, the beam propagation directions in the photonic crystal determined by two methods are approximately same. But in this paper, the results exhibit that there is an additional direction obtained by the finite difference time-domain method compared with the plane-wave expansion. Considering basic physical mechanism of the photon behavior, the present work circumvents the electromagnetic field distribution in the photonic crystal at a degenerate state, which can reasonably explain the phenomenon. Finally, it shows that a photonic crystal can be properly designed to achieve double refraction simultaneously at one frequency, which can also offer new thoughts and foundation for the novel beam splitter that applied to many optical systems.